The present invention relates to a fuel high pressure accumulator for a fuel injection system of an internal combustion engine, with a storage chamber and at least one connection pipe.
In such fuel high pressure accumulators, in the region of the intersection of the storage chamber inner wall and the opening which connects the storage chamber and the connecting pipe, stress peaks occur. There is therefore a danger that the fuel high pressure accumulator in this region can break, in particular since the storage chamber is subjected to dynamic pressure loads. In order to reduce the risk of breakage, various constraints have been provided. Therefore the pressure strength of the inventive fuel high pressure accumulator, in particular in the case of dynamic pressure loads, is increased.
One of the corresponding possibilities resides in increasing the wall thickness of the fuel high pressure accumulator. However the wall thickness of the fuel high pressure accumulator has certain limits since the thicked-walled body in condition of high dynamic pressure loads forms cracks, in particular in the region of wall openings and sharp-edged cross-sectional changes.
German patent document DE 196 40 480 A1 discloses a cylindrical fuel high pressure accumulator, in which the longitudinal axis of the opening which connects the storage chamber and the connection pipe is a secant of the circular storage chamber cross-section. Thereby a reduction of the stresses in the region of the intersection of the storage inner wall and the opening is achieved, so that the loading capacity and service life of the fuel high pressure accumulator are increased.
Accordingly, it is an object of the present invention to provide a fuel high pressure accumulator which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide the fuel high pressure accumulator with increased strength, in particular in condition of dynamic pressure loads.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a fuel high pressure accumulator for a fuel injection system of an internal combustion engines, which has a storage chamber limited by an inner wall, and at least one connecting pipe, wherein the connecting pipe has at least one connecting opening which opens into the storage chamber, and the inner wall in an intersecting region of the inner wall and the connecting opening is substantially flat.
When the fuel high pressure accumulator is designed in accordance with the present invention with the inner wall specifically designed in the intersection region with a connecting opening, then with the deformation of the fuel high pressure accumulator under pressure, pressure stresses are induced in the intersection region which, equalize a part of pulling stresses and stress picks resulting in the intersection region from the inner pressure, so that the pressure strength of the inventive fuel high pressure accumulater is increased.
The inner wall in the intersection region can be slightly concave or convex. The inventive advantages are also achieved with this curvature, so that in connection with the inventive feature of being substantially flat, a slightly concave or slightly convex curvature also falls under this feature.
In accordance with the present invention the storage chamber can be prismatic, so that it can be easily produced. For example, with corresponding spaces, the desired inner control of the fuel high pressure accumulator can be produced.
In accordance with a further embodiment of the present invention, the storage chamber can be ball-shaped. Therefore, regardless of the intersection regions with the connecting openings, a uniform stress condition in the fuel high pressure accumulator is provided.
In accordance with another embodiment of the present invention, the same advantages are achieved in a fuel high pressure accumulator for a fuel injection system of internal combustion engines having an outer wall, a storage chamber limited by an inner wall and at least one connecting pipe, wherein the connecting pipe has at least one connecting opening which opens into the storage chamber and the wall thickness of the fuel high pressure accumulator at least in the intersecting region of the inner wall and the connecting opening reduces and wherein the wall thickness of the fuel high pressure accumulator reduces in a region which is substantially opposite to the intersecting region of the inner wall and the connecting opening.
In this embodiment, the region of the fuel high pressure chamber which is opposite to the intersecting region deviates under pressure from outside outwardly, so as to also induce pressure stresses in the intersecting region. As a result, also the pulling stresses and stress peaks in the intersecting region of the fuel high pressure accumulator under pressure are reduced, so that its pressure strength is further increased.
The reduction of the wall thickness can be performed so that, the fuel high pressure accumulator at least in the region which is opposite to the intersecting region of the inner wall and the connecting opening has a transverse opening which extends substantially perpendicular to the longitudinal axis of the storage chamber and the connection opening. The reduction of the wall thickness can be performed in a simple manner in the already known fuel high pressure accumulator.
In accordance with another embodiment of the present invention, the outer wall at least in a region which is substantially opposite to the intersecting region of the inner wall and the connecting opening is flattened, so that the reduction of the wall thickness can be produced in a simple manner, for example by milling and leads to low stress peaks in the region of the reduced wall thickness. For further improvement or the stress condition in the fuel high pressure accumulator, it is provided that the flattening is flat or curved concavely or convexly and/or a chamfer or a rounding is provided in the outer wall.
The pressure strength of an inventive fuel high pressure accumulator is further increased, when the inner wall in an intersecting region is substantially flat while the storage chamber is prismatic or spherical, and the outer wall is provided with a transverse opening in an opposite region substantially perpendicular to a longitudinal axis of the storage chamber and can be flat, concave, convex and also provided with a chamfer or a rounding.
The manufacture of the inventive fuel high pressure accumulator can be simplified when it is assembled of a pipe with welded connecting pipes.